Portable electronic devices, for example, cellular or satellite telephones, laptop computers, personal digital assistants, electronic book readers, and the like, are fast becoming prevalent in everyday life. One of the services that have increased the desirability of these devices is the navigation guidance service that provides navigation guidance to an end user. Typically, these devices are equipped with one or more sensors for providing navigation guidance to the end user. For example, a portable communication device, may include, inertial or motion sensors (e.g., accelerometers, gyroscopes, compasses, etc.) capable of measuring locations, or orientations of the device, or Global Positioning System (GPS) receivers that may estimate geographic location of the device and then provide navigation guidance to a user based on the location.
One of the main issues with sensor based navigation guidance is the dependence on the measurement accuracy of the sensors. For example, the navigation guidance may be dependent on the accuracy of mobile device orientation measured by a compass sensor. Additionally, the quality of sensor based navigation guidance may also vary in different environments. For example, the quality of GPS sensor based navigation guidance may be low in an indoor environment, due to the low signal strength.